U.S. patent number 4,052,290 [Application Number 05/708,803] was granted by the patent office on 1977-10-04 for asphalt compositions.
This patent grant is currently assigned to Mobil Oil Corporation. Invention is credited to Donald R. Cushman, Charles A. Pagen, John W. Schick, Tsoung-Yuan Yan.
United States Patent |
4,052,290 |
Cushman , et al. |
October 4, 1977 |
**Please see images for:
( Certificate of Correction ) ** |
Asphalt compositions
Abstract
Improved asphalt compositions are provided which are produced by
forming a homogeneous blend of marginal asphalt stock with
coal-derived asphaltenes, and air-blowing the homogeneous blend to
yield an asphalt composition having a viscosity-penetration index
higher than about 2.5 .times. 10.sup.5.
Inventors: |
Cushman; Donald R. (Wenonah,
NJ), Pagen; Charles A. (Woodbury, NJ), Schick; John
W. (Cherry Hill, NJ), Yan; Tsoung-Yuan (Philadelphia,
PA) |
Assignee: |
Mobil Oil Corporation (New
York, NY)
|
Family
ID: |
24847246 |
Appl.
No.: |
05/708,803 |
Filed: |
July 26, 1976 |
Current U.S.
Class: |
208/6; 208/22;
208/3; 208/44 |
Current CPC
Class: |
C10C
3/04 (20130101) |
Current International
Class: |
C10C
3/00 (20060101); C10C 3/04 (20060101); C10G
003/00 () |
Field of
Search: |
;208/44,3,6,42 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: O'Keefe; Veronica
Attorney, Agent or Firm: Huggett; Charles A. Farnsworth;
Carl D.
Claims
What is claimed is:
1. A process for upgrading asphalt which consists essentially of
admixing and forming a homogeneous blend of coal-derived
asphaltenes with a marginal asphalt which has a potential air-blown
viscosity-penetration index lower than about 2.5 .times. 10.sup.5,
and air blowing the homogeneous blend to yield an asphalt
composition having a viscosity-penetration index higher than about
2.5 .times. 10.sup.5.
2. A process in accordance with claim 1 wherein the homogeneous
blending of asphalt and asphaltenes is conducted at a temperature
between about 200.degree. and 800.degree. F.
3. A process in accordance with claim 1 wherein the coal-derived
asphaltenes are employed in a quantity between about 1-50 weight
percent, based on the total weight of the composition.
4. A process in accordance with claim 1 wherein the asphaltenes are
derived from solvent refined coal.
5. A process in accordance with claim 1 wherein the asphaltenes are
derived from hydrogenated coal.
6. A process in accordance with claim 1 wherein the asphaltenes are
derived from coal tar.
7. An improved asphalt composition produced in accordance with the
process of claim 1.
Description
BACKGROUND OF THE INVENTION
Asphalt is an important large volume commodity which is generally
derived from petroleum refinery streams such as vacuum residua.
Air-blowing is normally required to increase the viscosity and
lower the penetration of the asphaltic material. During the
air-blowing process, thermal and oxidative polymerization is
effected, and the lower molecular weight resins are converted to
asphaltenes.
Continuing research and development efforts have provided a variety
of new and improved asphaltic compositions such as are described in
U.S. Pat. Nos. 2,395,041; 2,701,213; 2,721,830; 2,767,102;
2,807,596; 2,848,429; 2,894,904; 2,909,441; 3,146,118; 3,264,206;
3,374,104; 3,462,359; 3,476,679; 3,563,778; 3,707,388; 3,725,240;
3,779,964; 3,790,519; 3,810,771; 3,869,417; 3,915,914; and the
like.
Recent international economic developments have signaled the
inevitable decline of petroleum as the world's supreme industrial
commodity. The price of raw petroleum has increased several fold.
Also, the consumption of petroleum has been increasing
exponentially, and concomitantly the world petroleum supply has
diminished to less than several decades of proven reserves.
The economics of upgrading petroleum refining residua into asphalt
binders and other high value products is of increasing concern.
Attention is being directed to coal-derived liquids as a potential
abundant source of asphaltenes.
It was recognized by early workers that coal can be liquified by
controlled heating in the substantial absence of oxygen. The
conversion products are a liquid and a char. Because of the new
compelling economic factors, the technology of coal liquefaction
and gasification has been expanding at an accelerated pace. Pioneer
developments in the field are represented by Lurgi and
Fischer-Tropsch technology. More recent advances in coal
liquefaction are described in U.S. Pat. Nos. 1,904,586; 1,955,041;
1,996,009; 2,091,354; 2,174,184; 2,714,086; 3,375,188; 3,379,638;
3,607,718; 3,640,816; 3,642,608; 3,705,092; 3,849,287; 3,870,621;
inter alia.
One of the new developments in Fischer-Tropsch technology, i.e.,
the Sasol process, has been expanded into a commercial venture for
converting low grade coal into synthesis gas, and a broad spectrum
of organic derivatives such as fuel gas, light olefins, LPG,
gasoline, light and heavy fuel oils, waxy oils, and oxygenated
chemicals such as alcohols, ketones and acids. A byproduct of the
Sasol commercial operation is coal tar.
The prospective advantages of combining coal-derived materials with
petroleum-derived materials have not been readily achieved because
of the general incompatibility of the two different categories of
carbonaceous minerals.
Hence, there remains a pressing need for new technology to
alleviate the dependence of industrial nations on petroleum as a
critical raw material in energy and chemical applications, and a
need for new technology to enhance the efficient conversion of
petroleum refinery residua into valuable industrial products.
Accordingly, it is an object of the present invention to improve
the economics of upgrading low value refractory petroleum residua
into important industrial commodities.
It is another object of the present invention to provide a method
for producing homogeneous blends of coal-derived and
petroleum-derived materials.
It is another object of the present invention to provide a novel
class of asphalt compositions produced from coal-derived
carbonaceous material such as Sasol coal tar.
It is a further object of the present invention to improve the
air-blowing qualities of marginal asphalt stock.
Other objects and advantages of the present invention shall become
apparent from the accompanying description and examples.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. I is a drawing showing the properties of the base asphalt of
Example I compared with the asphalt compositions of Examples 2 and
3 before and after oxidation.
FIG. II is a drawing showing the properties of the base asphalt of
Example I compared with the asphalt composition of Example IV
before and after oxidation.
DESCRIPTION OF THE INVENTION
One or more objects of the present invention are accomplished by
the provision of a process which comprises admixing and forming a
homogeneous blend of coal-derived asphaltenes with a marginal
asphalt which has a potential air-blown viscosity-penetration index
lower than about 2.5 .times. 10.sup.5, and air-blowing the
homogeneous blend to yield an asphalt composition having a
viscosity-penetration index higher than about 2.5 .times.
10.sup.5.
By the term "viscosity penetration index" is meant the product of
viscosity of asphalt in stokes at 140.degree. F times penetration
at 77.degree. F/100 g/5 sec. In some countries, viscosity is
measured at 158.degree. F and vis pen is calculated accordingly. As
the air-blowing step of the invention process proceeds, the asphalt
composition viscosity increases and the penetration decreases.
Asphalt stocks which exhibit greater increase in
viscosity-penetration index in the blowing process are superior
stocks, because a higher viscosity-penetration index value
indicates disproportionally greater increase in viscosity (or
softening point) than the decrease in penetration.
The quality of an asphalt stock for air-blowing can be evaluated by
(1) a comparison of viscosity-penetration index at the same
penetration; or by (2) a comparison of the response of the asphalt
stock to air-blowing, i.e., the slope of viscosity-penetration
index versus penetration .alpha., in the equation log
(viscosity-penetration) equals .alpha.(penetration) + .beta., or
change of viscosity penetration index for each penetration number
at 45 penetration, .gamma..
The marginal asphalt component of the invention compositions can be
any of the various types of petroleum refinery asphalts and natural
asphalts which after air-blowing have a viscosity-penetration index
lower than about 2.5 .times. 10.sup.5. Marginal asphalts are
generally unsuitable as stocks for paving grade binders.
Illustrative of typical sources of marginal asphalt stocks are:
A. petroleum asphalts
1. Straight-reduced asphalts
a. Atmospheric or vacuum distillation
b. Solvent precipitation
2. Thermal asphalts, as residues from refinery cracking
operations
B. native or natural asphalts
1. Mineral content below 5 percent
a. Asphaltites such as gilsonite, grahamite, and glance pitch
b. Burmudez and other natural deposits
2. Mineral content over 5 percent
a. Rock asphalts
b. Trinidad and other natural deposits
There are two kinds of asphalt stocks which are well-known to have
poor qualities for air-blowing treatment:
1. Residuum of high hydrogen content, i.e., a low carbon-hydrogen
ratio. This type of stock contains higher paraffinic compounds
which are difficult to convert to resins and asphaltenes via
air-blowing.
2. Short residuum. When more and more valuable distillates are
driven off from petroleum crudes, the penetration of residua
becomes lower, and eventually straight-run asphalt results. If
additional distillates are removed, the resulting short residuum
cannot be blown to high viscosity without exceeding the lower limit
of penetration.
Asphalts are considered to be colloidal systems in which
asphaltenes constitute the dispersed phase and petrolenes the
dispersing phase. The petrolenes are defined as that portion of the
asphalt which is soluble in 50 volumes of normal pentane per volume
of asphalt. Asphaltenes have a high carbon to hydrogen ratio, which
indicates a highly aromatic composition. Asphaltenes are believed
to have a molecular weight between about 2000 and 10,000.
For the purposes of preparing improved asphalt compositions by the
present invention process, the coal-derived asphaltene component of
the homogeneous blending operation can be obtained by any of the
various coal solubilization and fractionation techniques
conventionally employed, e.g., solvent refining of coal.
By the term "solvent-refined" coal is meant any of the purified
carbonaceous materials produced by the steps of (1) liquefaction of
coal in a highly aromatic or partially hydrogenated aromatic
solvent (e.g., tetralin, anthracene, recycle coal oil, and the
like); (2) separation of a solvent-rich liquefaction phase from ash
and other undissolved solids; and (3) distillation of the
liquefaction phase to remove the solvent and volatile components of
the solution; and (4) recovery of the high boiling distillation
residuum as solvent-refined coal. For road paving and similar
applications, optionally the ash and undissolved solids can be
maintained in the compositions.
In a typical process, solvent-refined coal is produced by (1)
heating a mixture of powdered coal and recycle coal solvent (e.g.,
a distillation fraction recovered in a coal liquefaction process)
at a temperature of about 790.degree. F under a hydrogen pressure
of about 1000-2000 psi for a period of about one hour; (2)
separating the liquefaction phase from solids by filtration; (3)
distilling the liquefaction phase to remove the solvent and
volatile components which have a boiling point below about
600.degree. F at standard pressure; and (4) recovering
solvent-refined coal which is substantially free of ash and has a
much lower oxygen and sulfur content than the original coal
starting material. The solvent-refined coal is about 50 percent
soluble in benzene (insoluble in pentane) and about 50% soluble in
pyridine (insoluble in benzene). Table I summarizes the physical
and chemical characteristics of W. Kentucky and Illinois types of
coal, and the solvent-refined coal products derived therefrom in
accordance with hereinabove described liquefaction process.
The types of solvent-refined coal described in Table I contains
about 50 percent by weight of asphaltene components. Table II
summarizes the results of a chromatographic separation of
solvent-refined coal components. The asphaltenes appear to be a
mixture of polar hydrocarbons, indoles and benzofuran derivatives,
each of which is substituted with phenyl and/or naphthyl
groups.
Another source of coal-derived asphaltenes is from hydrogenated
coal products which are produced by liquefaction of coal in the
presence of a catalyst and a solvent under high hydrogen pressure
at a temperature between about 650.degree. and 750.degree. F.
Suitable catalysts include those containing metals such as
molybdenum, zinc, magnesium, tungsten, iron, nickel, chromium,
vanadium, palladium, platinum, and the like. High temperature,
sulfur-resistant catalysts such as molybdenum and tungsten sulfide
are preferred.
Coal tar is another excellent source of coal-derived asphaltenes.
Preferred coal tars are those having a softening point in the range
between about 100.degree. and about 350.degree. F, and a boiling
point in the range between about 500.degree. and about 1100.degree.
F. The highly preferred coal tars are those having a boiling point
in the range between about 600.degree. and about 1000.degree. F.
Suitable coal tars are those obtained from the pyrogenous treatment
of bituminous material (e.g., coke oven coal tar or pitch), and
from high temperature coal conversion processes such as the Lurgi
gasification process and the Sasol process.
TABLE I ______________________________________ W. Kentucky 14
Illinois #6 ______________________________________ Coal Coal Dry
SRC Dry SRC Dry Ash Free Product Dry Ash Free Product
______________________________________ C 72.98 79.0 87.6 70.22 79.4
85.3 H 5.12 5.9 4.8 4.75 5.4 5.6 N 1.33 1.4 2.0 1.42 1.6 1.8 S 3.06
3.3 0.8 3.22 3.6 0.9 Ash 8.48 -- 0.7 11.57 -- 1.5 O 9.03 9.8 3.4
8.82 9.9 4.3 Coal C.sub.100 H.sub.89 N.sub.1.5 S.sub.1.5 O.sub.9
Coal C.sub.100 H.sub.89 N.sub.1.5 S.sub.1.5 O.sub.9 SRC C.sub.100
H.sub.66 N.sub.1.9 S.sub.0.3 O.sub.2.9 SRC C.sub.100 H.sub.78
N.sub.1.8 S.sub.0.4 O.sub.3.8 7800 SCF H.sub.2 /ton coal Yield SRC
55% 8.5 atoms H/100 C ______________________________________
TABLE II
__________________________________________________________________________
FRACTIONS OBTAINED BY LIQUID CHROMATOGRAPHY ON SILICA GEL OF W.
KENTUCKY 14 SOLVENT REFINED COAL
__________________________________________________________________________
Oil-like Compounds Multifunctional Compounds.sup.2
Asphaltenes.sup.1 Fraction #1 #2 #3 #4 #5 #6 #7 #8 #9
__________________________________________________________________________
Eluent hexane hexane CHCl.sub.3 CHCl.sub.3 Et.sub.2 O MeOH
CHCl.sub.3 THF Pyridine 15% 4% 3% 3% 3% 3% benzene Et.sub.2 O EtOH
EtOH EtOH EtOH % in SRC.sup.3 0.4 15 30 10.2 10.1 4.1 6.4 10.2 8.5
__________________________________________________________________________
.sup.1 Asphaltenes defined as benzene-soluble, pentane-insoluble
compounds. .sup.2 Multifunctional products defined as
pyridine-soluble, benzene-insoluble compounds. .sup.3 This analysis
totals 94.9%, 5.1% of the SRC was not eluted from th column.
In the first step of the present invention process for producing
improved asphalt compositions, the marginal asphalt material and
the coal-derived asphaltenes are admixed and heated at a
temperature in the range between about 200.degree. and 800.degree.
F, and preferably in the range between about 300.degree. and
500.degree. F, for a period of time sufficient to provide a
homogeneous blend of the marginal asphalt and coal-derived
asphaltene components. The heating step is normally conducted for a
period of time between about 0.2 and 10 hours, and optionally under
pressure and/or in the presence of a reducing gas.
The coal-derived asphaltene component of the asphalt composition is
employed in a quantity between about 1 and 50 weight percent, based
on the combined weight of the coal-derived asphaltene and the
marginal asphalt components in the composition. For most
applications, the quantity of coal-derived asphaltenes will vary in
the range between about 3 and 30 weight percent.
After the step of forming a homogeneous blend of the marginal
asphalt and coal-derived asphaltenes is completed, the homogeneous
blend is subjected to a conventional air-blowing treatment to yield
the desired asphalt composition having a viscosity-penetration
index higher than about 2.5 .times. 10.sup.5.
Air-blowing conditions are described in U.S. Pat. Nos. 2,767,102;
3,462,359; and 3,707,388. In a typical air-blowing procedure, an
air rate of about 1.2 to 3.5 cubic feet per hour per pound of
charge is employed under atmospheric pressure at a temperature in
the range between about 400.degree. F and 800.degree. F.
The following Examples are further illustrative of the present
invention. The reactants and other specific ingredients are
presented as being typical, and various modifications can be
derived in view of the foregoing disclosure within the scope of the
invention.
EXAMPLE I
Conventional Asphalt Composition
A base asphalt derived from light Canadian crude was oxidized with
air at 325.degree. F for 75 minutes. The composition properties
before and after oxidation are listed in Table III. In FIG. 1
provided herein, the vis-pens at 65 and 45 penetration are
estimated to be 76,700 and 185,000, respectively. The response of
vis-pen to air-blowing as measured by .alpha. and .gamma. were
-0.0191 and -10,117, respectively.
EXAMPLE II
Invention Asphalt Composition
The same base asphalt as in Example I was admixed with 10 percent
by weight of bituminous coal liquefaction derivative, and the
admixture was oxidized with air in accordance with the procedure of
Example I.
The coal liquefaction derivative employed was a heavy viscous
hydrogenated coal oil distillate cut (950.degree. F) obtained by
treating finely divided bituminous coal (Illinois No. 6) with coal
oil recycle solvent (1 part coal/2 parts solvent) under hydrogen
pressure. The hydrogenation was carried out at a temperature of
800.degree.-850.degree. F, a hydrogen pressure of 2000-3000 p.s.i.
with a space velocity of 0.5-2 LHSV. The catalyst employed was a
currently available cobalt-molybdena alumina catalyst.
The composition properties before and after oxidation are set forth
in Table III and FIG. 1. The estimated vis-pens at 65 and 45
penetration were 140,000 and 290,000 (vs. 76,000 and 185,000 for
the base asphalt), respectively. The vis-pens of the invention
composition were significantly higher than those of the base
asphalt composition of Example I.
EXAMPLE III
Invention Asphalt Composition
The same base asphalt as in Example I was admixed with 10 percent
by weight of coal tar and the admixture was oxidized with air in
accordance with the procedure of Example I.
The coal tar employed was a Bethlehem coke oven tar backing at
650+.degree. F.
The composition properties before and after oxidation are set forth
in Table III and FIG. 1. The estimated vis-pens of the composition
at 65 and 45 penetration were 165,000 and 360,000 (vs. 76,700 and
185,000 for the base asphalt), respectively. The vis-pens of the
invention composition were more than twice those of the base
asphalt composition of Example I.
EXAMPLE IV
Invention Asphalt Composition
The same base asphalt as in Example I was admixed with 10 percent
by weight of a coal liquefaction bottoms fraction, and the
admixture was oxidized with air in accordance with the procedure of
Example I.
The coal liquefaction derivative was the 800.degree. F+ bottoms
fraction distilled off from the hydrogenated coal material prepared
in Example I.
The composition properties before and after oxidation are set forth
in Table II and FIG. 2. The results indicated that the sensitivity
of the invention composition to air-blowing as measured by .alpha.
and .gamma. was twice that of the base asphalt of Example I.
Table III ______________________________________ Oxidation of
Asphalt Example I II III ______________________________________
Composition Additive -- Coal Liquefaction Coal Distillate Tar
Additive, % 0 10 10 Base Asphalt, % 100 90 90 Before Oxidation
Viscosity at 140.degree. F, Stokes 1,180 566 971 Penetration at
77.degree. F 65 92 83 Vis-pen, modified 76,700 52,000 80,600 Air
Oxidized Product Viscosity at 140.degree. F, Stokes 5,376 10,655
6,010 Penetration at 77.degree. F 41 37 50 Vis-pen, modified
220,416 394,235 300,500 Vis-pen at 65 pen.sup.1 76,700 140,000
165,000 Vis-pen at 45 pen.sup.2 185,000 290,000 360,000
______________________________________ .sup.1 Vis-pen at 65
Penetration, see FIG. 1. .sup.2 Vis-pen at 45 Penetration, see FIG.
1.
Table IV ______________________________________ Oxidation of
Asphalt Example I IV ______________________________________
Composition Additive -- Coal Liquefaction Bottoms Additive, % 0 10
Base Asphalt, % 100 90 Before Oxidation Viscosity at 140.degree. F,
Stokes 1,180 2,029 Penetration at 77.degree. F 65 54 Vis-pen,
modified 76,700 109,566 Air Oxidized Product Viscosity at
140.degree. F, Stokes 5,376 29,838 Penetration at 77.degree. F 41
32 Vis-pen, modified 220,416 954,850 Slope, .alpha..sup.1 -0.0191
-0.0427 Sensitivity, .gamma..sup.2 -10,117 -27,042
______________________________________ .sup.1 Slope in the
equation, log (Vis-pen) = .alpha.(pen) + .beta.. .sup.2 Sensitivity
in terms of change in vis-pen/pen at 45 pen.
* * * * *